WO 2006/026240 A1 discloses a device for painting a curved outer surface of an aircraft, in this case a rudder unit of an aircraft. In order to apply picture motifs, a paint applicator is used that applies a pattern of drops of a pigment ink of at least one color onto the outer surface. The special pigment ink is polymerized by means of irradiation with ultraviolet light in order to harden and thusly render resistant the pigment ink. The special paint applicator is moved by means of a positioning device that is realized in the form of a gantry robot in order to move the paint applicator along the three dimensional axes, i.e., particularly also in the form of an advance movement for guiding the paint applicator along the curved outer surface. The desired picture motif is produced by converting a predetermined two-dimensional picture into three-dimensional driving data for the positioning device. A surface model of the outer surface of the aircraft is used for this purpose.
In this technical solution, it appears disadvantageous to utilize pigment ink that does not adhere to the outer surface in a very abrasion-resistant fashion despite the hardening process. During the operation of the aircraft, the picture motif may be damaged, in particular, due to mechanical erosion or the chemical effect of hydraulic oil residues. Although a picture motif with relatively high resolution can be produced with ink jet technology, its application requires a very long production time.
DE 10 2004 044 655 A1 discloses another technical solution for producing a picture motif on a curved outer surface of an aircraft, in which paint material is ejected by means of an inkjet head similar to the above-described inkjet technology. The picture motif is produced by means of a purposeful ejection and diversion of small droplets. This can be realized with a piezo-inkjet head or a thermo-inkjet head. The thusly designed paint applicator is moved along a bend guide rail that follows the curved surface of the aircraft, particularly the aircraft fuselage, in the form of a trolley. Alternatively, the paint applicator may also be arranged on the end of an articulated robot.
In this technical solution, it appears disadvantageous that the technology used is very similar to the inkjet technology that requires relatively long production times. Furthermore, this technology requires that the paint applicator is exactly guided a very short distance of no more than 1 mm from the curved outer surface, wherein this represents a significant challenge with respect to the control technology.